Abstract
In order to investigate the effect of split (pilot + main) injection on ignition and combustion characteristics of a D.I. Diesel engine, the in-cylinder combustion process was observed by using a bottom view type optical engine and a high speed video camera. The ignition and flame development processes as well as the rate of heat release were compared among various split injection strategies. Though the pilot injection makes the main injection spray flame more luminous and diffusive combustion type, splitting the pilot injection into two tiny pilots makes the main injection spray flame less luminous and more premixed
